DTRO Circular Flow Guide Disc

A disc tube reverse osmosis plant pushes high-concentration wastewater, often landfill leachate, through a stack of discs at pressure, and the spacer between those membranes decides whether the flow distributes evenly or channels and fouls. The disc shown here is that spacer: a moulded POM flow guide disc, flat and large in diameter, with the flow pattern cut into its central field.

The photograph shows the disc as moulded, with the central pattern of openings and the tight annular band that carries the stacking load. Everything about the part is dimensional discipline: a stack of hundreds of these discs only works if each one is the same.

Why POM

POM earns its place here through combination rather than any single property. It resists the chemicals carried in leachate, it holds its dimensions in warm, wet service where many resins creep, and it is slippery enough that surfaces contacting the membrane stack do not grab or shed particles. Its weakness is bonding and printing, which this part does not need; its strength is that a moulded disc comes out finished, with no machining and no secondary surface to contaminate the process stream.

The resin also moulds predictably in thin sections. A disc this diameter in a thin wall wants to warp, and POM’s crystallinity gives it enough stiffness after ejection to hold flat while it cools, provided the moulding gives it an even start.

Flatness Is the Product

The disc sits between membrane layers, and its whole function depends on presenting the same gap everywhere. A warp of a few tenths of a millimetre across the diameter changes the local channel height, and changed channel height is where flow concentrates, fouling starts and cleaning cycles shorten. Flatness is therefore the acceptance dimension, not a cosmetic one.

The tooling answers are the standard ones for a large thin part, applied without compromise: even wall, balanced cooling around the full diameter, generous cooling time before ejection, and an ejection layout that pushes on the stiff central field rather than the thin rim. Rushing any of these turns a good drawing into a stack of wobbly discs.

The Flow Pattern in the Centre

The central field carries the openings and ribs that distribute flow across the membrane face. The pattern is a hydraulic design decision, not a moulding one, and the mould has to reproduce it sharply: rib edges that come out rounded or flash-filled change the local flow and defeat the pattern the process was designed around. Cavity condition is maintained to the drawing because the steel is effectively the hydraulic profile.

The annular band outside the pattern is the mechanical half of the design. It takes the stacking load of the assembly, so its thickness and flatness hold the discs in register, and its surface is what the seals ride against. Where the band meets the patterned field, the section steps carefully, because a thick rim behind a thin field is where sink marks would appear on a part that cannot afford them.

Repeatability Across the Stack

A DTRO stack uses hundreds of identical discs, and the process performance depends on their similarity. Dimensional reports cover the pattern features, the band and flatness, sampled across each lot, with cavity-to-cavity consistency checked so that no one cavity drifts into producing discs that look fine alone and misbehave in a stack.

Information to Confirm Before Starting a Flow Guide Disc Project

• The disc drawing with the hydraulic pattern, since the tool reproduces it exactly.
• Stack pressure and temperature, which set the POM grade and the band thickness.
• Chemical exposure profile of the feed stream, confirming resin compatibility.
• Flatness tolerance and how it is measured, agreed before tooling rather than after.
• Annual volumes, since stack replacement demand usually justifies multi-cavity tooling.

Kunshan Maifeng Precision Industry Co., Ltd. reviews industrial component designs before quoting, builds the injection molds in house, and molds single-color and dual-color parts on 36 machines from 90 to 700 tons. Send us the disc drawing and the process conditions, and we will come back with a feasibility comment and a tooling proposal.

Company Profile

About Us

Kunshan Maifeng Precision Industry Co., Ltd. (MIF) has an investment of RMB 35 million and an independent factory of more than 5,000 m². The company operates 36 single- and dual-color injection molding machines from 90 to 700 tons, together with more than 50 sets of mold manufacturing and processing equipment. Our service, management and production team includes over 100 people.

Our parent company was established in 2008. We provide product design, mold design and manufacturing, injection molding and product assembly services for custom plastic parts, supporting both domestic and international customers.

1. Product Design
Product structure design and optimization based on customer drawings and samples.

2. Mold Design
Mold design developed around product geometry, material and production requirements.

3. Mold Manufacturing
Machining, polishing, fitting and assembly for custom injection molds.

4. Injection Molding
Single- and dual-color injection molding for project and order requirements.

5. Product Assembly
Supporting assembly services for molded plastic components.